3.6.3. T8R7R′ Compounds (R ) i-Bu) 2127 3.6.4. T8R7R′ Compounds (R ) Et, c-C5H9, or Cy) 2128 3.7. Mass Spectra of POSS Compounds 2128 3.8. Electronic Spectra of POSS Compounds 2130 3.9. NMR and EPR Spectroscopies 2131 3.9.1. Solution 29Si NMR Studies 2131 3.9.2. Other Heteronuclear NMR Studies 2134 3.9.3. EPR Spectra 2134 3.10. Vibrational Spectra of POSS Compounds 2136 3.11. X-ray Photoelectron Spectra of POSS Compounds 2139

Recent Developments in the Chemistry of Cubic Polyhedral Oligosilsesquioxanes

Surface modification and endothelialization of vascular biomaterials are common approaches that are used to both resist the nonspecific adhesion of proteins and improve the hemocompatibility and long-term patency of artificial vascular grafts. Surface modification of vascular grafts using hydrophilic poly(ethylene glycol), zwitterionic polymers, heparin or other bioactive molecules can efficiently enhance hemocompatibility, and consequently prevent thrombosis on artificial vascular grafts. However, these modified surfaces may be excessively hydrophilic, which limits initial vascular endothelial cell adhesion and formation of a confluent endothelial lining. Therefore, the improvement of endothelialization on these grafts by chemical modification with specific peptides and genes is now arousing more and more interest. Several active peptides, such as RGD, CAG, REDV and YIGSR, can be specifically recognized by endothelial cells. Consequently, graft surfaces that are modified by these peptides can exhibit targeting selectivity for the adhesion of endothelial cells, and genes can be delivered by targeting carriers to specific tissues to enhance the promotion and regeneration of blood vessels. These methods could effectively accelerate selective endothelial cell recruitment and functional endothelialization. In this review, recent developments in the surface modification and endothelialization of biomaterials in vascular tissue engineering are summarized. Both gene engineering and targeting ligand immobilization are promising methods to improve the clinical outcome of artificial vascular grafts.

/pdf/surface-modification-and-endothelialization-of-biomaterials-2qttnssa4b.pdf

Surface modification and endothelialization of biomaterials as potential scaffolds for vascular tissue engineering applications

Research into polymers incorporating polyhedral oligomeric silsesquioxane (POSS) has intensified during the past several years, revealing new fundamental polymer physics, new synthetic routes, and unexpected applications. The present review article critically examines the recent scientific literature on POSS polymers with an emphasis on structure-property relationships. We conclude that it is an exciting time to work on such materials and we expect the field to continue to grow in the foreseeable future.

POSS Polymers: Physical Properties and Biomaterials Applications

https://discovery.ucl.ac.uk/1376579/1/1376579.pdf

Skin regeneration scaffolds: a multimodal bottom-up approach

Ground-breaking advances in nanomedicine (defined as the application of nanotechnology in medicine) have proposed novel therapeutics and diagnostics, which can potentially revolutionize current medical practice. Polyhedral oligomeric silsesquioxane (POSS) with a distinctive nanocage structure consisting of an inner inorganic framework of silicon and oxygen atoms, and an outer shell of organic functional groups is one of the most promising nanomaterials for medical applications. Enhanced biocompatibility and physicochemical (material bulk and surface) properties have resulted in the development of a wide range of nanocomposite POSS copolymers for biomedical applications, such as the development of biomedical devices, tissue engineering scaffolds, drug delivery systems, dental applications, and biological sensors. The application of POSS nanocomposites in combination with other nanostructures has also been investigated including silver nanoparticles and quantum dot nanocrystals. Chemical functionalization confers antimicrobial efficacy to POSS, and the use of polymer nanocomposites provides a biocompatible surface coating for quantum dot nanocrystals to enhance the efficacy of the materials for different biomedical and biotechnological applications. Interestingly, a family of POSS-containing nanocomposite materials can be engineered either as completely non-biodegradable materials or as biodegradable materials with tuneable degradation rates required for tissue engineering applications. These highly versatile POSS derivatives have created new horizons for the field of biomaterials research and beyond. Currently, the application of POSS-containing polymers in various fields of nanomedicine is under intensive investigation with expectedly encouraging outcomes.

A nanocage for nanomedicine: polyhedral oligomeric silsesquioxane (POSS).

Background: Silicone implants are being used increasingly worldwide, especially in breast augmentation procedures. The most common morbidity observed is capsular contracture, which occurs in 15 percent of cases. To overcome this problem, the authors have developed a novel nanocomposite based on polyhedral oligomeric silsesquioxane-poly(carbonate-urea) urethane (POSS-PCU) for use as tissue implants.Methods: These polymers were implanted in six healthy sheep (n = 6) for 36 months and a siloxane served as the positive control. After explantation, these polymers were extracted, as was the surrounding capsule, if any. Attenuated total reflectance Fourier transform infrared spectroscopy analysis was performed to look for signs of surface degradation on the polymers and histopathologic and electron microscopic examinations were performed to study the interaction between the biomaterial and the host environment in greater detail.Results: After implantation, the authors observed minimal inflammation of the nanocomposite within the sheep model as compared with the siloxane control. Contact angle measurements and fibrinogen enzyme-linked immunosorbent assay tests were then conducted on the POSS-PCU nanocomposite to determine the reason for this behavior. The increased fibrinogen adsorption on POSS-PCU, its amphilicity, and large contact-angle hysteresis indicated that POSS-PCU inhibits inflammation by adsorbing and inactivating fibrinogen on its surface. In complete contrast, the control siloxane in the same setting demonstrated very significant inflammation and degradation, resulting in capsular formation. Naturally, there was no evidence of degradation of the nanocomposite compared with the siloxane control.Conclusions: POSS-PCU nanocomposites have enhanced interfacial biocompatibility and better biological stability as compared with conventional silicone biomaterials, thus making them safer as tissue implants.

Silsesquioxane Nanocomposites as Tissue Implants

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Silsesquioxane Nanocomposites as Tissue Implants